"""

"""
from util import pr


class A:
    def __getitem__(self, item):
        if not isinstance(item, int):
            return 'a'
        if item > 10:
            raise IndexError
        return item


class B(A):
    def __contains__(self, item):
        return item == 'a'


a = A()
b = B()
pr('a' in a, 3 in a, 'b' in a, 'a' in b, 3 in b)
